Changing Etiology of Zoonotic Dermatophytosis: Perspective of Human Medicine
Dermatophytes are still an important public health problem in both “developed” and “developing” countries, and their prevalence remains high. Zoophilic dermatophytes remain frequent causative agents and should be considered especially in children and adolescents with tinea capitis and tinea of glabrous skin.
Changes in epidemiological patterns and prevalence of dermatophytosis in domestic animals are commonly detected secondarily from epidemiological studies on human population because of better surveillance and more complex epidemiological data.Tinea capitis is a typical clinical entity caused predominantly by zoophilic species in majority of developed countries. Microsporum canis is a prevalent causal agent, and this could be related to close association between humans and companion animals and mass tourism to endemic regions (such as the Mediterranean area). Exceptional situation is currently in Germany, where T. benhamiae prevails over M. canis. Studies in Europe, Asia, and Africa indicate that anthropophilic agents of scalp infections are being almost eradicated and are now more typical of countries with low socioeconomic status. The exception is tinea capitis due to T. tonsurans in North America. A shift toward tinea capitis due to anthropophilic dermatophytes (T. tonsurans, T. soudanense, and M. audouinii) is obvious in some urban areas in Europe, e.g., from the UK, France, Sweden, and Switzerland. This pattern seems to be linked to ethnic groups originating from Africa or from the Caribbean. Various anthropophilic species remain major causal agents of tinea capitis in many Asian and African countries, although significant shift toward zoophilic etiology (similar to situation in Europe) was observed in numerous more developed regions during last decades as described in detail, e.g., from China (Havlickova et al. 2008; Seebacher et al. 2008; Nweze 2010; Hayette and Sacheli 2015; Kieliger et al.
2015; Uhrlaβ et al. 2015; Zhan et al. 2015; Nweze and Eke 2016). Exceptionally, other zoophilic species such as T. mentagrophytes or T. verrucosum may represent the major agents of tinea capitis as reported, e.g., from some region of China, Middle East, or Africa (Al-Duboon et al. 1999; Metin et al. 2002; Nweze 2010; Oudaina et al. 2011; Zhan et al. 2015).Epidemiologic changes in the prevalence and etiology of inflammatory dermatophytoses on bare skin have been less extensively studied. Their prevalence and pathogens responsible for causing them usually reflect local trends in tinea capitis and tinea pedis. In general, broad spectrum of anthropophilic, zoophilic, and geophilic species can be responsible for similar clinical manifestation. Various anthropophilic species cause majority of infections in developed as well as in developing countries, and zoophilic species such as M. canis, T. mentagrophytes, and T. verrucosum supplement the spectrum of the most important causative agents worldwide. Microsporum canis still prevails over anthropophilic species in South European countries, although increase of anthropophilic species was observed in the most recent studies. Trichophyton verrucosum and T. mentagrophytes remain predominant dermatophytes in rural regions of the Middle East (Naseri et al. 2013; Hayette and Sacheli 2015; Chadeganipour et al. 2016).
Zoophilic dermatophytes also importantly contribute to a number of occupational infections in farmers, workers in livestock production, laboratory workers, pet shop workers, and other professions that require contact with animals (McAller 1980; Cafarchia et al. 2013c; Halsby et al. 2014). Incidence of dermatophytosis in farm workers can be strikingly high (Torres-Rodriguez et al. 1992; Agnetti et al. 2014).
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